Wondering about machining some billet or 304 stainless at aprox. 3/16 for the manifold and downpipe. It looks quite clear to me that the rotary's heat is gone blow the 1/32 oe gaskets/flanges so I thought I should beef it up a lil bit. Has anyone else tried this? Or does someone know if there would be any probs? By the way its an s4 t2 with s5 block and turbo but s4 intake system.thanks

 

"1/32 oe gaskets/flanges " You mean original equipment gaskets, as in what mazda makes? Those hold up QUITE WELL!

 

iv never had any issues with any of the OE manifold gaskets blowing, minus the water O-ring gasket internally. Iv seen on numerous 150k+ rotary engines with still intact OE gaskets, almost to the point where they look hardly used. I believe unlike piston engines our gaskets don't experience the same wear and stress.

 

hmm see i have trouble with leaks , at only 94k on the car . you can excessive see carbon build up all around the down pipe flange and slight at the mani and smoke trails while at idle .

 

Try a little permatex ultra copper on the gasket. Also you can take everything apart and make sure the manifold flanges are flush. They do take a lot of heat, and they may be slightly warped.

 

quite about a 1/2 to 11/16 from one point to another after they were removed

 

The OEM gaskets are extremely high quality. If you look at them closely, you will see that they are multiple layers and not just a stainless sheet. A 304 stainless gasket would NOT seal well due to the fact that stainless is a hard metal and it will not conform to the surface. Especially if it is 3/16" thick.

The OEM gaskets are blowing out for you because the surfaces they are trying to seal are warped.

 

As Aaron said there is nothing better than the OEM gaskets on the exhaust, that applies to a lot of things not just our cars. Ours are also priced accordingly, they are very expensive.
The two biggest reasons exhaust gaskets blow out are either a warped surface as stated above or an exhaust restriction that is making excessive back pressure.
Look at your cats and mufflers and flanges and repair accordingly.

 

well that isnt the case in mine , the back pressure prob. You are indeed correct Aaron , both gasket are multiple layers but the gaskets are extremely warped while the block and manifold are fine the down pipe however is warped.